update CHANGELOG

Author: mitchellh

CHANGELOG.md

@@ -4,6 +4,7 @@
   without `mapstructure` (or the configured tag name) set [GH-277]
 * Decoding to slice from array no longer crashes [GH-265]
 * Decode nested struct pointers to map [GH-271]
+* Fix issue where `,squash` was ignored if `Squash` option was set. [GH-280]
 
 ## 1.4.3